Stomach lining cells 2 days Platelets 10 days

Stomach lining cells: 2 days ___________ Platelets: 10 days ___________ Skin Cells: 20 days ___________ Red Blood Cells: 120 days ___________ Intestinal lining cells: 3 days ___________ Brain cells: 30 -50 years ___________

• DNA plus proteins is called chromatin. chromatid • One half of a duplicated chromosome is a chromatid. • Sister chromatids are held together at the centromere. • Telomeres protect DNA and do not include genes. telomere centromere telomere Condensed, duplicated chromosome

• The four stages of the cell cycle are gap 1, synthesis, gap 2, and mitosis. 1) Gap 1 (G 1): cell growth and normal functions 2) DNA synthesis (S): copies DNA 3) Gap 2 (G 2): additional growth 4) Mitosis (M): includes division of the cell nucleus (mitosis) and division of the cell cytoplasm (cytokinesis) • Mitosis occurs only if the cell is large enough and the DNA undamaged.

Mitosis and cytokinesis produce two genetically identical daughter cells. Parent cell • Interphase prepares the cell to divide. • During interphase, the DNA is duplicated. nucleus with DNA centrioles spindle fibers centrosome

Sister Chromatids Nuclear Membrane Shorten and Thicken Begins to break down Centrioles Move apart from one another Fibers Form between centrioles

Sister Nuclear Chromatids Membrane Become attached to the fibers. Are pulled to middle of cell Remains dissolved Centrioles Move to opposite ends of cells Fibers Are stretched between the two ends of cell

Sister Nuclear Chromatids Membrane Pulled apart by fibers. Each chromatid is separate from its “sister” Remains dissolved Centrioles Still at cell’s poles; Fibers Pull each chromatid toward opposite ends of cell

Sister Nuclear Chromatids Membrane Each end of cell has a complete set of chromosomes. Begins to reform Cell Membrane Begins to pinch, forming two new cells Fibers Begin to disappear

• Cytokinesis differs in animal and plant cells. – In animal cells, the membrane pinches closed. – In plant cells, a cell plate forms.

Cell’s Life Cycle: Mitosis: • Interphase • Prophase • Metaphase • Anaphase • Telophase • Interphase _______________ _______________ _______________ _______________ _______________

The process is VERY SIMILAR in each type of cell. There are only 2 differences: 1. Plant cells do not have centrioles 2. A cell wall is laid down at the end of the cell division.

_______________ Life Cycle Animation

Cell division is uncontrolled in cancer. • Cancer cells form disorganized clumps called tumors. • Benign tumors remain clustered and can be removed. • Malignant tumors metastasize, or break away, and can form more tumors. normal cell cancer cell bloodstream

• Cancer cells do not carry out necessary functions. • Cancer cells come from normal cells with damage to genes involved in cell-cycle regulation.

• Carcinogens are substances known to promote cancer. • Standard cancer treatments typically kill both cancerous and healthy cells.

ORGANISM CAT DOG CHIMPANZEE EARTHWORM GOLDFISH CARROT LETTUCE ONION CHICKEN GUINEA PIG HUMAN MOSQUITO PEA PENICILLIN CORN FROG “GUESSTIMATE” ACTUAL CHROMOSOME # 32 78 48 36 94 18 18 16 78 64 46 6 14 1 -4 20 26

Stem cells are unique body cells. • Stem cells have the ability to – divide and renew themselves – remain undifferentiated in form – develop into a variety of specialized cell types

• Stem cells are classified into three types. – totipotent, or growing into any other cell type – pluripotent, or growing into any cell type but a totipotent cell – multipotent, or growing into cells of a closely related cell family

• Stem cells come from adults and embryos. – Adult stem cells can be hard to isolate and grow. – The use of adult stem cells may prevent transplant rejection. – The use of embryonic stem cells raises ethical issues – Embryonic stem cells are pluripotent and can be grown indefinitely in culture. First, an egg is fertilized by a sperm cell in a petri dish. The egg divides, forming an inner cell mass. These cells are then removed and grown with nutrients. Scientists try to control how the cells specialize by adding or removing certain molecules.

• The use of stem cells offers many currently realized and potential benefits. – Stem cells are used to treat leukemia and lymphoma. – Stem cells may cure disease or replace damaged organs. – Stem cells may revolutionize the drug development process.